Gene silencing by RNA molecules has been implicated in a wide variety of physiological pathways including pathologies such as cancer and the control of cell proliferation, cell death, fat metabolism, neuronal patterning, modulation of hematopoietic lineage differentiation, and control of leaf and flower development. Accordingly, there is increasing demand for methods for detecting and quantifying RNA molecules involved in gene regulation.
Conventional methods and standards for detecting and quantifying the presence of RNA molecules employ technologies such as gene chips or arrays. The presence of a specific RNA molecule can be detected when, for example, the target RNA molecule binds to a complementary sequence on an array. Small RNA molecules including microRNA (miRNA), tiny non-coding RNA (tncRNA), short interfering RNA (siRNA) and small modulatory RNA (smRNA) can be difficult to detect because of their size, copy number, and susceptibility to enzymatic degradation. The number of copies of such a small RNA present in a sample can be minuscule compared to the presence of other transcripts and the small RNA can be undetectable because of overwhelming signal from abundant non-target RNA transcripts.